18 July 2015
The Neoproterozoic Purcell Sill is a stark, obvious black stripe in the strata of Glacier National Park. Here it is emerging from behind “The Salamander” glacier, above Grinnell Glacier Cirque:
Zooming in, you can see the “baked” (bleached) zones above and below this concordant intrusion.
But this time, during my visit to this special place, I noticed a discordant offshoot from the main sill:
See it? Up there at the head of that valley:
Zooming in further, you can see four people standing on the contact metamorphosed zone on the left side of this dike:
I went and searched for it in Google Maps, and found it quite easily emerging from that icy valley;
How this escaped my notice during my previous trips to this site, I’ll never know. I was glad to find something new there, though.